Just something whacky to get you thinking. At least it got me pulling apart my hair, and now, I'm half bald.

Saturday, March 19, 2011

Node.js as "the next BIG thing".

I generally hate to talk about "the next BIG thing" because there seem to be (relatively) fewer things (as compared to all the things that we encounter) that influence our lives in significant ways these days (simply because we encounter so many things these days).

However, I feel that node.js is going to be quite influential in the years to come.

So, what is "node.js"? Node (put briefly) is a javascript execution engine. It incorporates asynchronous I/O as part of its design and hence can be considered asynchronous by design. This is where it starts getting fascinating for me.

Do you remember all those $.ajax() requests you made in the browser? Well, what if you could so the same on the server side? What if stitching together a page on the server was as easy as making AJAX calls and filling in empty <div> tags? You needn't stretch your imagination too much because that's exactly what Node lets you do!!

Even more exciting is that fact that this asynchronous API isn't limited to just HTTP/AJAX calls, but extends to protocols such as SMTP, POP, XMPP, and Database handlers such as PGSQL, MySQL, and Sqlite. This is because the Socket & file system I/O on Node is asynchronous by design. (almost??) All the APIs which do I/O are asynchronous in nature. For some, blocking counterparts are provided solely for convenience.

Toy task: Make 10 HTTP web calls and present the output as the result of each of these 10 calls separated by a new line. Assume that each HTTP call takes 1 sec to produce the result.

You notice that the code takes 10 sec to run - 1 sec for each HTTP web call. We ignore the time taken to write out the results.

Sample code (using non-blocking I/O):

out = "";
res [10] = [ ];
for i = 1 to 10:
# We assume that http_call does NOT block and retiurns immediately,
# processing the task in the background (another thread or using
# non-blocking I/O)
res[i] = http_call(url);
for i = 1 to 10:
# We assume that the when statement blocks execution till the
# condition is met
when res[i].complete:
out += (res[i].data + "\n");
write_output(out);

You notice that the code takes 1 sec to run - 1 sec for each HTTP web call; all of which fire at the same time. We ignore the time taken to write out the results.

That's a phenominal increase of 10x from the blocking version. Now, why wouldn't anyone use Node for such a use case??